Yamaizumi M, Uchida T, Takamatsu K, Okada Y
Proc Natl Acad Sci U S A. 1982 Jan;79(2):461-5. doi: 10.1073/pnas.79.2.461.
The erythrocyte ghost function method was used to introduce 125I-labeled diphtheria toxin, its fragments A and B, and two labeled crossreacting material (CRM), mutant proteins CRM176 and CRM197, into cultured mouse cells. Fragment A was relatively stable in mouse cytoplasm at 37 degrees C and at least 80% was recovered from cells after 24 hr of incubation. In contrast, wild-type fragment B and A fragments from CRM176 and CRM197 were unstable and were degraded with half-lives of about 2.5 hr under similar conditions. When a rabbit anti-fragment A IgG fraction was introduced with wild-type A, the rate of degradation of A was accelerated, whereas the rates of degradation of A176 and A197 were retarded by the same antibody. In every instance the degradation rate appeared to be that of the IgG fraction itself with a half-life of about 7.5 hr.
采用红细胞血影功能法，将125I标记的白喉毒素、其A片段和B片段，以及两种标记的交叉反应物质（CRM）、突变蛋白CRM176和CRM197导入培养的小鼠细胞中。A片段在37℃的小鼠细胞质中相对稳定，孵育24小时后，至少80%可从细胞中回收。相比之下，野生型B片段以及CRM176和CRM197的A片段不稳定，在类似条件下的半衰期约为2.5小时，会发生降解。当将兔抗A片段IgG组分与野生型A一起导入时，A的降解速率加快，而A176和A197的降解速率则受到相同抗体的抑制。在每种情况下，降解速率似乎就是IgG组分本身的降解速率，半衰期约为7.5小时。
